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VMS Help CC, Messages, UNSIGNEDPRES *Conan The Librarian |
Message <Context> the conversion of the unsigned char/short
value "<expression>" to unsigned int shows one
example of this program's use of unsigned-preserving
integral promotion. This differs from the
value-preserving semantics of standard C compilers.
Description This expression shows one of possibly many places
where this compilation uses unsigned-preserving
semantics for small integer promotions rather than
value-preserving semantics required of standard C
compilers. In cases where an unsigned char or
unsigned short int is promoted to an integer, there
are two different ways the convert could happen.
Standard C requires that the type be converted to a
signed int (value-preserving semantics) while some
older compilers will convert to an unsigned int
(unsigned-preserving semantics). The difference in
the choice of int or unsigned int can have an impact
on results of expressions that use the converted
value. The compiler cannot determine whether or not
a particular instance of this usage will cause an
observable behavior difference in the program. For
more information, consult Section 3.2.1.1 of the
Rationale for ANSI C.
User Action Be aware that standard compilers might interpret this
expression differently.
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